LED white light illuminator

ABSTRACT

The invention provides an LED lighting device and method that produces high intensity, spatially uniform, white light in the near and far fields in a reduced package size that does not significantly heat the surrounding environment, wherein the white light is produced by using a phosphor layer in conjunction with at least one LED.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/334,525 filed on Dec. 30, 2002, now U.S. Pat. No. 7,153,015, bearingthe title, LED WHITE LIGHT OPTICAL SYSTEM, the entire contents of whichis incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to a white-light optical system, and moreparticularly, to a LED white-light optical system that providesspatially uniform high intensity white light over a near field divergingregion in a highly efficient manner.

BACKGROUND OF THE INVENTION

Many optical energy applications require high intensity, spatiallyuniform, white light that does not significantly heat the surroundingenvironment in the near field and/or far field. More specifically, manyapplications require correlated color temperatures between 4100-4900K(i.e., white light) with a color rendering index (“CRI”) between 90 to100.

Correlated color temperature (“CCT”) is a numerical assignment of theapparent color of a light source (i.e., as viewed by the human visualsystem) and is measured in degrees Kelvin. Color rendering is how well alight source renders color (i.e., in the course of interacting with anobject) as compared to how well daylight renders color (i.e., in thecourse of interacting with the same object).

Traditional light sources, however, suffer from, for example, but notlimited to, combinations of a poor CRI, poor CCT, poor intensity, shortusage life, large power electrical consumption, large package size,thermal energy, and/or are electrically and; or optically inefficient.

Tungsten filament lamps. for example, while providing high intensityoptical energy with high CRI values, emit optical energy that has a poorCCT (i.e., about 3000K. which correlates to the color yellow) for whitelight applications. In addition. tungsten filament lamps have a lowelectrical to optical efficiency and, thus, require large amounts ofelectrical power to generate high intensity optical energy, whichresults in large quantities of thermal energy. Furthermore. high powertungsten lamps have a low lamp lifetime, usually operating for about 500hours.

Tungsten-halogen lamps, when used in conjunction with filters, produce aCCT of above 4000K but still suffer from many of the same disadvantagesof Tungsten filament lamps.

Metal halide lamps have a high luminous efficiency (“electric energy” to“optical energy” efficiency) and produce optical energy with a CCT ofaround 5000K (bluish white), which is just above the white light range.However. Metal halide lamps also emit optical energy below and above thehuman visual system. The optical energy above the white light CCT rangeis referred to as infrared light. Infrared light optical energy issensed as thermal energy or heat. The optical energy below the whitelight CCT range is referred to as ultra violet light and in manycircumstances an unwanted or damaging byproduct. Xenon arc lamps provideoptical energy with higher intensity than metal halide lamps. but have alow luminous efficiency and low lamp life time (around 500 hours).Furthermore, traditional light sources such as arc lamps, for example,when used as a light source for a less than spherical illuminationregion, are optically inefficient. The full spherical discharge ofoptical energy is difficult to capture into a particular illuminationregion.

A light emitting diode (“LED”) emits optical energy over specific CCT'swithin the white light CCT range. However, commercially available LED'sthat emit white light have low CCT and have poor control. In addition,LED's provide insufficient optical energy for most illuminationapplications.

An improved optical system is needed.

SUMMARY OF THE INVENTION

A preferred embodiment of the invention provides a LED lighting devicethat produces high intensity, spatially uniform, white light in the nearand far fields in a reduced package size that does not significantlyheat the surrounding environment, wherein the white light is produced byusing a phosphor layer in conjunction with a single LED.

An alternative embodiment of the invention provides a method forobtaining high intensity, spatially uniform, white light in the near andfar fields in a reduced package size that does not significantly heatthe surrounding environment, wherein the white light is produced byusing a phosphor layer in conjunction with a single LED.

A preferred embodiment of the invention provides an LED curing devicethat produces high intensity, spatially uniform, optical energy forcuring in the near and far fields in a reduced package size that doesnot significantly heat the surrounding environment, wherein the opticalenergy is produced by using single and multiple LED's.

A preferred embodiment of the invention provides a method for obtaininghigh intensity, spatially uniform, optical energy for curing in the nearand far fields in a reduced package size that does not significantlyheat the surrounding environment, wherein the optical energy is producedby using single and multiple LED's.

A preferred embodiment of the invention provides a LED photo-dynamictherapy device that produces high intensity, spatially uniform, opticalenergy for photo-dynamic therapy in the near and far fields in a reducedpackage size that does not significantly heat the surroundingenvironment, wherein the optical energy is produced by using single andmultiple LED's and single and multiple concentrators.

A preferred embodiment of the invention provides a method for obtaininghigh intensity, spatially uniform, optical energy for photo-dynamictherapy in the near and far fields in a reduced package size that doesnot significantly heat the surrounding environment, wherein the opticalenergy is produced by using single and multiple LED's and single andmultiple concentrators.

An alternative embodiment of the invention provides a LED illuminationdevice that produces high intensity, spatially uniform, white light inthe near and far fields in a reduced package size that does notsignificantly heat the surrounding environment, wherein the white lightis produced by using an array of different color LEDs and single andmultiple concentrators.

An alternative embodiment of the invention provides a method forobtaining high intensity, spatially uniform, white light in the near andfar fields in a reduced package size that does not significantly heatthe surrounding environment, wherein the white light is produced byusing an array of different color LED's and single and multipleconcentrators.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of the invention will become apparent from the followingdetailed description considered in connection with the accompanyingdrawings. It is to be understood, however, that the drawings aredesigned as an illustration only and not as a definition of the limitsof the invention.

In the drawings, wherein similar reference characters denote similarelements through the several views:

FIG. 1 illustrates a white light system according to a preferredembodiment of the invention,

FIG. 2 illustrates a flow diagram of the white light system according toa preferred embodiment of the invention,

FIG. 3 illustrates a LED curing system according to an alternativeembodiment of the invention,

FIG. 4 illustrates a LED photodynamic therapy system according to analternative embodiment of the invention, and

FIG. 5 illustrates a multi-wavelength LED array illumination system 500according to an alternative embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Applications, including, but not limited to, indication, illumination,curing, photo-dynamic therapy, scanning, etc., require optical energywith specific characteristics, such as, but not limited to, wavelengthspectrum, a CCT range, a CRI value, angular distribution, intensity,and/or spatial distribution, high electrical-to-optical power conversionefficiency, etc.

Optical energy, in general, includes the optical wavelength spectrumfrom 100 nanometers wavelength to 20 microns wavelength and includes thevisual light spectrum, the infrared spectrum, and the ultraviolet lightspectrum. The visual light spectrum is from 380 nanometers wavelength to750 nanometers wavelength, the infrared spectrum is from 700 nanometerswavelength to 20 microns wavelength and the ultraviolet spectrum is from100 nanometers to 380 nanometers. The wavelength spectrum or spectrumwidth of optical energy refers to the wavelengths present within theoptical energy. A uniform wavelength spectrum occurs when the wavelengthspectrum is the same spectrum at each point within a region of theoptical energy.

Intensity of optical energy is defined as the power per unit area. Thus,the intensity of optical energy in a diverging illumination pattern willdecrease as the distance from the optical energy source increases (i.e.,since the unit area increases).

Spatial distribution of optical energy is the intensity (as defined aspower per unit area) at each point in a particular target area relativeto the entire illuminated area. Uniform spatial distribution occurs whenthe optical energy per unit area is constant.

Angular distribution is the direction of the emitted optical energy. Forexample, the sun emits light over the entire area of the sun's surface.The area of a sphere equals 4π times the square of the radius. Inoptics, this is referred to as 4π steradians for a sphere and 2πsteradians for a hemisphere. Thus the angular distribution of the sun is4π steradians: However. light sources, other than the sun, emit light atless than 4π steradian, due to the geometry of creating or deliveringthe optical energy. An LED emits optical energy out the face (when theLED is encapsulated) of the LED into a hemisphere (i.e., 2π steradian).

Also, optical energy is defined as being in the near field or the farfield. Optical energy is referred to as near field if the region ofinterest is within ten times the diameter of the source. Thus for anoptical element with an exit aperture of ten millimeters, the near fieldis the region within 100 millimeters of the exit aperture and the farfield is the region past 100 millimeters.

Optical energy systems utilize optical elements to manipulate, direct,filter, etc. optical energy to better prepare the optical energy for aparticular application. Thus, between the optical energy source and theend application there may be multiple optical elements. Optical elementsinclude any element capable of interacting with optical energy and caninclude elements such as, but not limited to, filters, reflectors,diffractors, refractors, aligners, lenses, concentrators, polarizers,micro-structures, etc. Four characteristics of an optical interactioninclude scatter, transmission, fluorescence and phosphorescence,absorption and reflection of the optical energy (i.e., photons).

Thus for example, optical energy interacting with a filter will scattera percentage of the optical energy, transmit through the filter apercentage of optical energy, absorb a percentage of the optical energy,and reflect a percentage of the optical energy. The magnitude of thesepercentages is a function of the optical energy and of the filter.

Optical efficiency is the ratio of total optical power that reaches adesired target area to the total optical power initially received and/orcreated by a given optical system.

A preferred embodiment of the invention increases optical efficiencyover conventional optical systems by utilizing index matching. Theoptical efficiency of an interface between a first and second medium ispotentially affected by the index of refraction of each medium.Everything from air to optical element materials has an associated indexof refraction. In order for there not be any optical energy loss, due tototal internal reflection, the index of refraction of the second elementmust be equal to or less than the index of refraction of the firstelement, referred to as index matching. When there is no index matching,the amount of optical energy passed from the first element to the secondelement is reduced, thereby reducing the optical efficiency.

A preferred embodiment of the invention increases optical efficiencyover conventional optical systems by utilizing flush connections. Theoptical efficiency of an interface between a first and second medium ispotentially affected by flushness of the physical interface connection.Two optical elements are flush if there are no impurities orirregularities between the two attaching surfaces (also referred to asbeing in optical contact). A flush connection allows the optical energyto pass from one medium to a second medium without any loss of opticalefficiency.

A preferred embodiment of the invention increases optical efficiencyover conventional optical systems by geometrically matching opticalelements. The optical efficiency of an interface between a first andsecond medium is potentially affected by the geometric shapes of eachmedium. A second medium entrance aperture shape that is the same orlarger than a first medium exit aperture shape ensure that all theoptical energy, when transmitting from a first medium exit aperture iscaptured by the second medium entrance aperture.

Referring to the drawings and in particular to FIGS. 1-5, there areshown preferred embodiments of the invention.

FIG. 1 illustrates a white light system 100 according to a preferredembodiment of the invention. The optical system 100 includes a LEDoptical source 110, an optical filter 120, a reflector 130, a phosphorlayer 135, a concentrator 140, a first illumination region 150, asecondary optical element 160, a second illumination region 170, atarget 180, and a thermal dissipater 190.

The LED optical source 110 provides optical energy. The LED opticalsource110 includes optical material 115 with a front face 111 and backface 112.

Electrical current is provided to the LED by power source (not shown).An LED provides optical energy at particular CCT ranges. When anelectrical field is applied across a LED semiconductor junction, photonsare released within the semiconductor material. The Photons emit in a 4πsteradian angular distribution and exit the LED via the front and backface. The semiconductor material determines the CCT range of the createdoptical energy.

In a preferred embodiment of the invention, the LED optical source frontface 111 emits optical energy over a 2π steradian distribution. In analternative embodiment of the invention, the LED optical source backface 112 emits optical energy over a 2π steradian distribution.

In an alternative embodiment of the invention, LED optical source 110 isthermally connected to the thermal dissipater 190. In an alternativeembodiment, LED optical source 110 is any source that emits opticalenergy at the desired CCT range, at the desired optical energy level andover a 2π steradian distribution.

In a preferred embodiment of the invention, the LED optical source frontface 111 surface area is flat. In a preferred embodiment of theinvention, the LED optical source front face 111 surface area iscircular. In an alternative embodiment of the invention, the LED opticalsource front face 111 surface area is square. In a preferred embodimentof the invention, the LED optical source back face 112 surface area isflat. In a preferred embodiment of the invention, the LED optical sourceback face 112 surface area is circular. In a preferred embodiment of theinvention, the LED optical source back face 112 surface area is square.

Optical energy (i.e., photons) are created by a light emitting diode(“LED”) by the injection of electrical current into a semiconductorjunction. The electrical current is injected by an electrical powersource such as, but not limited to, an electrical wall plug, a battery,a fuel cell, a generator, etc. The selection of LED semiconductormaterial for the p and n type junctions determines the CCT range of thecreated optical energy emitted from the LED and dictates the amount ofthermal energy produced by the LED as a result of the creation ofoptical energy from electrical energy.

In an alternative embodiment of the invention, LED optical source 110can be any light source that produces optical energy. In an alternativeembodiment of the invention, LED optical source 110 is an array of LEDs.In an alternative embodiment of the invention, LED optical source 110 isan array of nine LEDs placed in close proximity to each other.

In an alternative embodiment of the invention, electrical current isdelivered to the LED semiconductor junction within the LED material 115through a wire that connects a bond pad, which is positioned at thesemiconductor junction on the LED, to electrically conducting goldposts, which pierce (or go through) a header. A header mounts orattaches the LED. In a preferred embodiment. the header attaches the LEDto the heat dissipater 190. The bond pad is the contact point forinjecting electrical current into the semiconductor junction and thewire is an aluminum wire 0.0025 inches in diameter. The gold postselectrically attach to the electrical power source.

In an alternative embodiment, an electrically conducting material ispositioned on the LED optical source back face 112. In an alternativeembodiment of the invention, the electrically conducting material is agold plate positioned on the LED optical source back face 112. In analternative embodiment, the cathode (or negative polarity) is positionedon the LED optical source back face 112. In an alternative embodiment,the anode (or positive polarity) is positioned on the LED optical sourcefront face 111.

In an alternative embodiment, an encapsulating layer is positioned onthe LED optical source front face 111. The encapsulate protects thealuminum wires from external forces that may cause the electricalconnection to break. In an alternative embodiment, the encapsulate isMasterbond UV 15-7.

In a preferred embodiment of the invention, the index of refraction ofthe encapsulate is the same as the index of refraction of the phosphorlayer 135. In an alternative embodiment, the index of refraction of theencapsulate is greater than the index of refraction of the phosphorlayer 135. In a preferred embodiment of the invention, the index ofrefraction of the encapsulate is the same as the index of refraction ofthe concentrator 140. In an alternative embodiment, the index ofrefraction of the encapsulate is greater than the index of refraction ofthe phosphor layer 135.

In FIG. 1, electrical power is supplied to the LED optical source 110 bya power source. The power source is electrically attached to LED opticalsource 110. In a preferred embodiment of the invention, the power sourceis a battery. In a preferred embodiment of the invention, the powersource is an electrical wall socket. In a preferred embodiment of theinvention, the power source is a fuel cell.

In FIG. 1, reflector 130 is a reflective optical element positioned toreflect optical energy emitted from the LED optical source back face 112back into the LED optical source 110. The reflector has a front face 131that reflects optical energy and a back face 132 that attaches tothermal dissipater 190. In a preferred embodiment of the invention, thereflector reflects optical energy back into the LED optical material 115through the LED back face 112. The optical energy then interacts withthe optical material and a portion of the optical energy will exit LEDfront face 111 and interacts with the optical filter 120. In a preferredembodiment of the invention, the reflector 130 is a mirror. In analternative embodiment of the invention, reflector 130 filters outoptical energy in the infrared spectrum.

In a preferred embodiment of the invention, the reflector 130 is anoptical coating applied directly onto the LED optical source back face112. In a preferred embodiment of the invention, the reflector 130 is anoptical coating applied directly onto the thermal dissipater 190. In apreferred embodiment of the invention, the reflector 130 reflectsoptical energy at a CCT range of 6000K to 8000K.

In a preferred embodiment of the invention, the reflector front face 131is flush with the LED optical source back face 112. In a preferredembodiment, the reflector front face 131 surface area shapegeometrically corresponds to the LED optical source back face 112surface area shape. In an alternative embodiment of the invention, thereflector front face 131 surface area shape is larger than the LEDoptical source back face 112 surface area shape. In an alternativeembodiment of the invention, the reflector front face 131 is smallerthan the LED optical source back face 112 surface area shape.

In a preferred embodiment of the invention, the reflector front face 131surface area is flat. In a preferred embodiment of the invention, thereflector back face 132 surface area is flat. In a preferred embodimentof the invention, the reflector front face 131 surface area shape iscircular. In a preferred embodiment of the invention, the reflector backface 132 surface area is circular.

In FIG. 1, the optical filter 120 is positioned after LED optical sourcefront face 111. Optical filter 120 includes a front face 121 and a backface 122. The optical energy emitted from LED optical source front face111 enters optical filter back face 122 and interacts with opticalfilter 120. The optical energy is then reflected back out optical filterback face 122 or transmitted through optical filter front face 121,notwithstanding the slight amount of optical energy that is scatteredand/or absorbed.

The optical filter 120 includes a reflected CCT range and a transmittedCCT range. Optical energy that is within the reflected CCT range isprohibited from passing through the optical filter 120 (e.g., viareflection). Optical energy that is within the transmitted CCT rangepasses through the optical filter 120. In a preferred embodiment of theinvention, the optical filter 120 transmits optical energy at a CCTrange of 6000K to 8000K and reflects optical energy at a CCT range of2500K to 6000K.

In a preferred embodiment of the invention, the optical filter frontface 121 emits optical energy over a 2π steradian distribution. In apreferred embodiment of the invention, the optical filter back face 122emits optical energy substantially over a 2π steradian distribution.

In a preferred embodiment of the invention, the optical energy spatialdistribution emitted through optical filter front face 121 is uniform.In a preferred embodiment of the invention, the optical energy spatialdistribution emitted through optical filter back face 122 is uniform.

In a preferred embodiment, the optical filter back face 122 is flushwith the LED optical source front face 111. A flush connection allowsthe optical filter back face 122 to capture 2π steradian angulardistribution of optical energy from the LED optical source front face111.

In a preferred embodiment of the invention, the optical filter 120 is anoptical coating. In an alternative embodiment of the invention, theoptical filter 120 is a dielectric stack coated directly onto the LEDoptical source front face 111.

In a preferred embodiment of the invention, the optical filter back face122 surface area is flat. In a preferred embodiment of the invention,the optical filter back face 122 surface area is circular. In analternative embodiment of the invention, the optical filter back face122 surface area is square. In a preferred embodiment of the invention,the optical filter front face 121 surface area is flat. In a preferredembodiment of the invention, the optical filter front face 121 surfacearea is circular. In a preferred embodiment of the invention, theoptical filter front face 121 surface area is square.

In a preferred embodiment, the optical filter back face 122 surface areashape geometrically corresponds to the LED optical source front face 111surface area shape. A geometrically corresponding connection allows theoptical filter back face 122 to interact with all of the optical energybeing emitted from the LED optical source front face 111. In analternative embodiment of the invention, the optical filter back face122 surface area shape is larger than the LED optical source front face111 surface area shape. In an alternative embodiment of the invention,the optical filter back face 122 is smaller than the LED optical sourcefront face 111 surface area shape.

In a preferred embodiment, the filter includes a stack of one fourth ofthe wavelength of light layers of alternating high and low refractiveindex to create the desired filtering characteristics.

In an alternative embodiment of the invention, the surface area shape ofthe optical Filter 120, in reference to the concentrator 140, isoptimized to reflect particular CCT ranges. CRI values, and/or intensityvalues required in the first and/or second illumination regions.

In FIG. 1, the phosphor layer 135 is positioned to capture opticalenergy emitted from the optical filter front face 121. The phosphorlayer 135 includes a back face 137, which receives optical energy fromoptical filter front face 121, a front face 136, which emits opticalenergy into said concentrator 140, and sides 138.

The phosphor layer 135 comprises material that when stimulated byoptical energy of a particular CCT range (i.e., the stimulated CCTrange), creates and emits new optical energy at a different CCT range(i.e., the phosphor-created CCT range) and, at the same time, allowsnon-stimulated optical energy (i.e., the non-stimulated CCT range) totransmit through the phosphor layer. In addition, the phosphor layer135, as an optical element, allows a certain percentage of opticalenergy of the stimulated CCT range (i.e., that is not absorbed by thephosphor) to transmit through the phosphor layer (i.e., due toscattering).

Phosphor layer characteristics, such as, but not limited to, the amountof phosphor doping, the spectrum involved, and the thickness of thephosphor layer all affect the intensity and the wavelength spectrum thatis emitted by the phosphor layer. The interaction of optical energy withthe phosphor layer is an isotropic process resulting in an opticalenergy being emitted over a 4π distribution. Thus, optical energy emitsout the phosphor layer back face, 137, the front face 136, and the sides138.

In a preferred embodiment, optical energy enters the phosphor layer backface 137 and the optical energy within the stimulated CCT range,stimulates the phosphor within the phosphor layer 135 creating newoptical energy within a phosphor-created CCT range. The new opticalenergy within the phosphor-created CCT range, when combined with opticalenergy that enters the phosphor layer back face 137 that is in thenon-stimulated CCT range provides optical energy that corresponds towhite light. In a preferred embodiment of the invention, optical energyemits from phosphor layer front face 136 that corresponds to white lighton the CCT range.

In an alternative embodiment of the invention, the phosphor layercharacteristics are modified or adjusted to ensure optical energy of aspecific CCT range emits from phosphor layer front face 136.

A small percentage of optical energy is emitted out of the sides 138 ofthe phosphor layer (i.e., side loss). In a preferred embodiment of theinvention, the amount of side loss is decreased by coating the interiorside wall with a reflective material. In an alternative embodiment ofthe invention, the amount of side loss is decreased by reducing thesurface area of the sides. In an alternative embodiment of theinvention, side loss is reduced by placing the sides in contact with amedium of lower refractive index.

In a preferred embodiment of the invention, optical energy emitting fromthe phosphor layer back face 137 enters the optical filter 120 throughthe optical filter back face 122. The optical filter 120 includes areflected CCT range and a transmitted CCT range. Optical energy that iswithin the reflected CCT range is prohibited from passing through theoptical filter 120 (e.g., via reflection). Optical energy that is withinthe transmitted CCT range passes through the optical filter 120.Accordingly, the optical energy that enters the optical filter frontface 121 from the phosphor layer back face 137 that is in the opticalfilter 120 reflected CCT range will be reflected back into the phosphorlayer 135 and the optical energy that is in the optical filter 120transmitted CCT range will transmit through the optical filter 120 andinto the LED optical source 110, but for losses associated withabsorption and scattering.

In a preferred embodiment of the invention, the optical energy thatenters the optical filter 120 from the phosphor layer 135 that is in theoptical filter 120 transmitted CCT range transmits through the opticalfilter 120 and into the LED optical source 110 and then interacts withthe optical reflective element 130. At that point, the optical energy isreflected back into the LED material 115 and then transmits to theoptical filter 120. Since the optical energy is within the opticalfilter transmission wavelength spectrum, the optical energy passesthrough the filter and into the Phosphor Layer. whereupon the opticalenergy interacts with the phosphor layer thereby providing a repeatingtelescoping circular process for the optical energy that emits out ofthe phosphor layer back face 137. This repeating process capturesoptical energy that would otherwise be lost.

In a preferred embodiment of the invention, the Phosphor layer 135 isPhosphor Technologies Yttrium Aluminum Oxide: Cerium QMK58/F-U1. In apreferred embodiment of the invention, the phosphor layer 135 is 0.254millimeters thickness. In a preferred embodiment of the invention, thephosphor layer stimulated CCT range is 6000K to 8000K. In a preferredembodiment of the invention, the phosphor layer phosphor created CCTrange is 2500K to 6000K.

In a preferred embodiment of the invention, the spatial distribution ofthe optical energy emitted through the phosphor layer front face 136 isuniform. In a preferred embodiment of the invention, the spatialdistribution of the optical energy emitted through the phosphor layerback face 137 is uniform.

In a preferred embodiment, the phosphor layer back face 137 is flushwith the optical filter front face 121. In a preferred embodiment, thephosphor layer back face 137 surface area shape geometricallycorresponds to the optical filter front face 121 surface area shape. Inan alternative embodiment of the invention, the phosphor layer back face137 surface area shape is larger than the optical filter front face 121surface area shape. In an alternative embodiment of the invention, thephosphor layer back face 137 is smaller than the optical filter frontface 121 surface area shape.

In a preferred embodiment of the invention, the phosphor layer frontface 136 surface area is flat. In a preferred embodiment of theinvention, the phosphor layer back face 137 surface area is flat. In apreferred embodiment of the invention, the phosphor layer front face 136surface area shape is circular. In a preferred embodiment of theinvention, the phosphor layer back face 137 surface area shape iscircular.

In an alternative embodiment of the invention, the thickness of thephosphor layer is optimized to stimulate particular CCT ranges, CRIvalues, and/or optical energy values required in the first and/or secondillumination regions. In an alternative embodiment of the invention, thesurface area shape of the phosphor layer 135, in reference to theconcentrator 140, is optimized to stimulate particular CCT ranges, CRIvalues, and/or optical energy values required in the first and/or secondillumination regions.

In FIG. 1, the concentrator 140 is positioned to capture optical energyemitting out of the phosphor layer front face 136. The concentrator 140has an entrance aperture 142, which receives optical energy from thephosphor layer front face 136, and an exit aperture 141, which outputsoptical energy into the first illumination region 150. The concentrator140 captures optical energy up to a two pi steradian distribution viathe entrance aperture 142, aligns the optical energy via total internalreflection, and then outputs the aligned optical energy through the exitaperture 142 into a three dimensional symmetrical pattern or region,referred to as the first illumination region 150.

In a preferred embodiment of the invention, the concentrator entranceaperture 142 is fully filled. In a preferred embodiment of theinvention, the concentrator exit aperture 142 is fully filled. Theentrance aperture is fully filled when entrance aperture receivesoptical energy over the entire entrance aperture.

In a preferred embodiment, the concentrator 140 is a non-imagingconcentrator. A non-imaging concentrator provides a divergingillumination pattern. A concentrator provides a high degree of lightcollection. The theoretical throughput performance of a circularnon-imaging concentrator is one hundred percent collection efficiencyand close to ninety six percent of the collected optical energy exitsthrough the exit aperture within the solid angle as defined by theconcentrator physical characteristics. The approximate four percent lossis attributed to rim loss. A trough concentrator approaches 100%efficiency. The ideal profile of a non-imaging concentrator is acompound parabola, which is referred to as a compound parabolicconcentrator (“CPC”). In a preferred embodiment of the invention,concentrator 140 is a CPC. In a preferred embodiment of the invention,the profile of concentrator 140 is determined by the angularillumination region requirements of the optical system. The referenceWelford, Winston, “High Collection Nonimaging Optics”, Academic Press,Inc. '89, ISBN 0-12-742885-2, which is hereby incorporated by reference,provides a detailed discussion of nonimaging optics.

Non-imaging concentrators maintain etundue. The etundue formula holdsthat the input numerical aperture multiplied by the input optical energyspatial extent equals the output numerical aperture multiplied by theoutput optical energy spatial extent.

In an alternative embodiment of the invention, the non-imagingconcentrator has a profile constructed with a high order polynomialsurface representing the attributes of the non-imaging concentratorform. In an alternative embodiment of the invention, the aspheric sagequation is tuned to match an appropriate non-imaging concentrator. Inan alternative embodiment, the circumference of the concentrator isfaceted. The higher the number of facets, the closer the facetedconcentrator comes to producing the results of a circular concentrator.In a preferred embodiment of the invention, the concentrator emitsoptical energy with a CCT range of 4100K to 4900K. In a preferredembodiment of the invention, the concentrator emits optical energy thatcorresponds to white light according to the human visual system. In apreferred embodiment of the invention, the spatial distribution of theoptical energy emitted through the non-imaging concentrator exitaperture 142 is uniform.

In a preferred embodiment of the invention, the concentrator entranceaperture 141 is flush with the phosphor layer front face 136. In apreferred embodiment of the invention, the concentrator entranceaperture 142 surface area shape geometrically corresponds to thephosphor layer front face 136 surface area shape. In an alternativeembodiment of the invention, the concentrator entrance aperture 142surface area shape is larger than the phosphor layer front face 136surface area shape. In an alternative embodiment of the invention, theconcentrator entrance aperture 142 is smaller than the phosphor layerfront face 136 surface area shape.

In a preferred embodiment of the invention, the index of refraction ofthe concentrator 140 is the same as the index of refraction of thephosphor layer 135. In an alternative embodiment, the index ofrefraction of the concentrator 140 is less than the index of refractionof the phosphor layer 135.

In a preferred embodiment of the invention, the concentrator entranceaperture 142 surface area is flat. In a preferred embodiment of theinvention, the concentrator exit aperture 141 surface area is flat. In apreferred embodiment of the invention, the concentrator entranceaperture 142 surface area shape is circular. In a preferred embodimentof the invention, the concentrator exit aperture 141 surface area shapeis circular.

In FIG. 1, the first illumination region 150 is positioned to receiveoptical energy emitted from the concentrator 140. The optical energythat emits from the concentrator 140 has a corresponding angulardistribution. This angular distribution of the optical energy formsdiverging angles that define the first illumination region 150. Thefirst illumination region 150 has a first illumination region back face152, which defines the beginning area of the first illumination pattern,and a first illumination region front face 151, which defines the endarea of the first illumination pattern. In a preferred embodiment of theinvention, the first illumination region 150 is a diverging conicalthree-dimensional region and is defined by the angular distributioncharacteristics associated with concentrator 140.

The first illumination region 150 is located in a first illuminationmedium. In a preferred embodiment of the invention, the first medium isair. In a preferred embodiment of the invention, the first illuminationmedium does not require sides to bound or to direct the optical energyin the first illumination region since the optical energy in firstillumination region is aligned.

In a preferred embodiment of the invention, the index of refraction ofthe first medium has a value of one. In a preferred embodiment of theinvention, the index of refraction of the first medium is the same asthe index of refraction of the concentrator 140. In an alternativeembodiment of the invention, the index of refraction of the first mediumis less than the index of refraction of the concentrator 140. In apreferred embodiment of the invention, the first illumination region 150contains optical energy with a CCT range of 4100K to 4900K. In apreferred embodiment of the invention, the first illumination regionfront face 151 emits optical energy with a CCT range of 4100K to 4900K.In a preferred embodiment of the invention, the first illuminationregion contains optical energy that corresponds to white light accordingto the human Visual system. In a preferred embodiment of the invention,the first illumination region front face 15I emits optical energy thatcorresponds to white light according to the human visual system. In apreferred embodiment of the invention, the spatial distribution of theoptical energy emitted through the first illumination region front face152 is uniform.

In FIG. 1, the secondary optical element 160 is positioned to receiveoptical energy from the first illumination front face 151. The secondaryoptical element 160 includes a back face 162, which receives opticalenergy from the first illumination region 150 via first illuminationfront face 151, and a front face 161, which emits optical energy to asecond illumination region 170.

In a preferred embodiment of the invention, the secondary opticalelement 160 is a prism: and re-directs the aligned optical energypresent in the first illumination region 150 to a second illuminationregion 170. In a preferred embodiment of the invention, optical element160 is positioned within the near field of the concentrator 140.

In an alternative embodiment, secondary optical element 160 is anyoptical element that alters the optical energy present in the firstillumination region 150. Optical elements include, but are not limitedto, a prism, lens, filter, concentrator, mirror, refractive element,diffractive element, wavelength modifier, intensity modifier,phosphorous layer, light pipe, etc. Optic energy can be alteredaccording to, for example, but not limited to, spatial distribution,wavelength spectrum, intensity and angular distribution.

In a preferred embodiment of the invention, the secondary opticalelement back face 162 is flush with the first illumination region frontface 151. In a preferred embodiment of the invention, the secondaryoptical element back face 162 surface area shape geometricallycorresponds to the first illumination region front face 151 surface areashape. In an alternative embodiment of the invention, the secondaryoptical element back face 162 surface area shape is larger than thefirst illumination region front face 151 surface area shape. In analternative embodiment of the invention, secondary optical element backface 162 is smaller than the first illumination region front face 151surface area shape.

In a preferred embodiment, the index of refraction of the secondaryoptical element 160 is the same as the index of refraction of the firstmedium. In an alternative embodiment, the index of retraction of thesecondary optical element 160 is less than the index of refraction ofthe first medium.

In an alternative embodiment of the invention, the secondary opticalelement entrance aperture 162 is positioned to receive optical energyfrom the concentrator exit aperture 141. The optical energy that entersthe secondary optical element has an angular distribution as defined bythe geometric shape of the concentrator.

In a preferred embodiment of the invention, the secondary opticalelement back face 162 is flush with the concentrator exit aperture 141.In a preferred embodiment of the invention, the secondary opticalelement back face 162 surface area shape geometrically corresponds tothe concentrator exit aperture 141 surface area shape. In an alternativeembodiment of the invention, the secondary optical element back face 162surface area shape is larger than the concentrator exit aperture 141surface area shape. In an alternative embodiment of the invention,secondary optical element back face 162 is smaller than the concentratorexit aperture 141 surface area shape.

In a preferred embodiment, the index of refraction of the secondaryoptical element 160 is the same as the index of refraction of theconcentrator 140. In an alternative embodiment, the index of refractionof the secondary optical element 160 is less than the index ofrefraction of the concentrator 1140.

In a preferred embodiment of the invention, the secondary opticalelement back face 162 surface area is flat. In a preferred embodiment ofthe invention, the secondary optical element front face 161 surface areais flat.

In a preferred embodiment of the invention, the secondary opticalelement back face 161 Surface area shape corresponds to the surface areaof the interface between the illumination region and the secondaryoptical element back face 161. In a preferred embodiment of theinvention, the secondary optical element back face 162 surface areashape is circular. In a preferred embodiment of the invention, thesecondary optical element front face 161 surface area shape is circular.In a preferred embodiment of the invention, the secondary opticalelement back face 162 surface area shape is oval. In a preferredembodiment of the invention, the secondary optical element front face161 surface area shape is oval.

In an alternative embodiment of the invention, when the secondaryoptical element 160 is a reflector, optical energy reflects off of thesecondary optical element back face 162 and is redirected into adifferent direction, such as, but not limited to, back into theconcentrator 140, back into the first illumination region 150, into asecond illumination region 170, and/or into a second illumination region170 that partially overlaps the first illumination region 150.

In a preferred embodiment of the invention, the secondary opticalelement front face 161 emits optical energy with a CCT range of 4100K to4900K. In a preferred embodiment of the invention, the secondary opticalelement back face 162 reflects optical energy with a CCT range of 4100Kto 4900K. In a preferred embodiment of the invention, the secondaryoptical element front face 161 emits optical energy that corresponds towhite light according to the human visual system. In a preferredembodiment of the invention, the secondary optical element back face 162reflects optical energy that corresponds to white light according to thehuman visual system. In a preferred embodiment of the invention, thespatial distribution of the optical energy emitted from the secondaryoptical element front face 162 is uniform.

In FIG. 1, the second illumination region 170 is positioned to receiveoptical energy emitted (and/or reflected) from the secondary opticalelement 141. The optical energy that emits (and/or reflects) from thesecondary optical element 141 has a corresponding angular distribution.The angular distribution of the optical energy forms diverging anglesthat define the second illumination region 170. The second illuminationregion 170 has a second illumination region back face 172, which definesthe beginning area of the second illumination pattern, and a secondillumination region front face 171, which defines the end area of thesecond illumination pattern and is also referred to as the target area.In an alternative embodiment, the second illumination pattern extendspast the target area. In a preferred embodiment of the invention, thesecond illumination region 170 is a diverging conical three dimensionalregion and is defined by the angular distribution characteristicsassociated with secondary optical element 160.

The second illumination region 170 is located in a second illuminationmedium. In a preferred embodiment of the invention, the second medium isair. In a preferred embodiment of the invention, the second illuminationmedium does not require sides to bound or to direct the optical energyin the second illumination region since the optical energy in secondillumination region is aligned.

In a preferred embodiment of the invention, the index of refraction ofthe second medium has a value of one. In a preferred embodiment of theinvention, the index of refraction of the second medium is the same asthe index of refraction of the secondary optical element 160. In analternative embodiment of the invention, the index of refraction of thesecond medium is less than the index of refraction of the secondaryoptical element 160.

In a preferred embodiment of the invention, the second illuminationregion 170 contains optical energy with a CCT range of 4100K to 4900K.In a preferred embodiment of the invention, the second illuminationregion front face 171 emits optical energy with a CCT range of 4100K to4900K to a target 180. In a preferred embodiment of the invention, thesecond illumination region contains optical energy that corresponds towhite light according to the human visual system. In a preferredembodiment of the invention, the second illumination region front face171 emits optical energy that corresponds to white light according tothe human visual system to a target 180. In a preferred embodiment ofthe invention, the spatial distribution of the optical energy emittedfrom the second illumination region front face 172 to a target 180 isuniform.

In a preferred embodiment of the invention, the second medium is flushwith the secondary optical element front face 161. In an alternativeembodiment of the invention, the second medium is flush with thesecondary optical element back face 162.

In FIG. 1, the target 180 is positioned at the second illuminationregion front face 171. Optical energy present at the second illuminationfront face 171 interacts with the target 180 and reflects to the humanvisual system. In an alternative embodiment of the invention, the target180 is located within the second illumination region 170.

In FIG. 1, the thermal dissipater 190 is thermally attached to the LEDoptical source 110. The thermal dissipater 190 dissipates thermal energypresent in the white light system 100. In an alternative embodiment ofthe invention, the thermal dissipater 190 is thermally attached at anyplace in the white light system 100, including, but not limited to theLED optical source 110, the power source, the optical reflector 130, theoptical filter 120, the phosphor layer 135, the concentrator 140, thefirst illumination region 150, the first medium, the secondary opticalelement 160, the second illumination region 170, the second medium,and/or the target 180, etc.

Thermal energy results from the creation of photons from electricity. Inaddition, optical energy within the infrared spectrum provides thermalenergy. Infrared radiation has longer wavelengths than the visiblespectrum and is sensed as thermal energy or heat.

In an alternative embodiment of the invention, an intercepting opticalelement, such as, but not limited to, a filter, a reflector, orabsorber, etc., is positioned within white light system 100 to interceptoptical energy in the infrared system. The thermal dissipater 190 isthen thermally attached to this intercepting optical element.

In a preferred embodiment, the heat dissipater 190 is a heat sink. In analternative embodiment of the invention, a header (not shown) is used tomount or attach the LED optical source 110 to the heat dissipater 190.In an alternative embodiment of the invention, the header is thermallyconductive, thereby allowing thermal energy present in the LED opticalsource to transfer to the heat dissipater 190.

In an alternative embodiment, the header is electrically conductive,thereby providing an electrical connection for electrical power to reachthe LED optical source 110. In an alternative embodiment of theinvention, the header material includes copper. In an alternativeembodiment of the invention, the header is formed into a thin cylinder.

In an alternative embodiment, the heat dissipater includes fins. Thefins increase the surface area of the heat dissipater, which increasesthermal dissipation.

In an alternative embodiment of the invention, a heat spreader ispositioned between the heat sink and the LED optical source 110. Theheat spreader is thermally attached to the LED optical source 110 andpulls the thermal energy away from the thermal energy source anddisburses the thermal energy laterally (i.e., the LED optical source110). Increased thermal dissipation provides for increased electricefficiency within the LED. In an alternative embodiment of theinvention, the heat spreader material includes diamond. Diamond has ahigh thermal conductivity and thus permit higher operating currents tobe used without increasing the temperature of the LED. In an alternativeembodiment of the invention, the heat spreader material includes anymaterial with a high conductivity, such as, but not limited to copper,aluminum, etc. The heat spreader is thermally attached to the thermaldissipater 190 and/or the heat sink.

FIG. 2 illustrates a flow diagram of the white light system according toa preferred embodiment of the invention. Referring to the elementsillustrated in FIG. 1, in the first step. (step 205) a light sourceprovides optical energy at a particular spectrum. In a preferredembodiment of the invention, the light source is an LED optical source110, which creates photons when a current field is applied across theLED semiconductor junction. In a preferred embodiment of the invention,the created photons have a 4π steradian angular distribution. In apreferred embodiment of the invention, the electric power is provided tothe LED optical source by a power source. The thermal energy produced bythe LED optical source is dissipated by a thermal dissipater 190. In apreferred embodiment of the invention, the thermal dissipater is a heatsink, which dissipates the heat. In an alternative embodiment of theinvention, a header (not shown) is used to attach the heat sink to theLED optical source. In an alternative embodiment of the invention, aheat spreader (not shown) is used to distribute the thermal energy fromthe LED optical source to the heat sinks. In a preferred embodiment ofthe invention. the white light system 100 merges the optical energycreated by the LED optical source and the optical energy created by thephosphor layer 135 to produce white light.

In the next step, (step 210) the photons interact within the LEDsemiconductor junction. The photons within the semiconductor junctionemit in the direction of the LED optical source back face 112 and in thedirection of the LED optical source front face 111. There is some lossdue to optical scattering and absorption.

It is next determined (step 215) whether the photons in the LED aretraveling toward the LED optical source back face 112. The photons thatreach the LED optical source back face 112 interact with a reflector 130(step 220) and the photons that are within the reflected spectrum arereflected back into the LED optical source 110 (step 210). Since thereflected optical energy is traveling in a direction towards the LEDoptical source front face 111, the reflected optical energy has a highprobability of reaching the LED optical source front face 111. Thus, theoptical efficiency of the white light system 100 is improved by theaddition of a reflector to capture otherwise lost optical energy. In analternative embodiment of the invention, the reflected spectral width istailored to optimize the production of white light by the white lightsystem 100.

The photons that reach the LED optical source front face 111 interactwith an optical filter 120 (step 225). The optical filter 120 has areflected spectral width and a transmitted spectral width. The opticalenergy that is within the reflected spectral width is reflected out ofthe face the optical energy interfaced the filter. The optical energythat is within the transmitted spectral width is transmitted through theoptical filter. In a preferred embodiment of the invention, the opticalfilter 120 is coated directly onto the LED front face 111. In analternative embodiment of the invention, the reflected spectral widthand the transmitted spectral width is tailored to optimize theproduction of white light by the white light system 100.

It is next determined if the optical energy interacting with the opticalfilter 120 is within the transmitted spectrum (step 230). If the opticalenergy is not within the transmitted spectrum, it is next determinedfrom what direction the optical energy came from (step 235). If theoptical energy that is not in the transmitted spectrum entered (orinterfaced with) the optical filter back face 122, then the opticalenergy is reflected back into the LED optical source 110 (step 210). Inthe example, since the LED does not provide optical energy within theoptical filter spectrum, very little optical energy will be reflectedaccording to this particular step, but for that associated withscattering. However, if it is determined (see step 235) the opticalenergy, that is not in the optical filter transmitted spectrum, entered(or interfaced with) the optical filter front face 122, then the opticalenergy reflects back into the phosphor layer 135 to interact with thephosphor layer (step 245).

On the other hand, if it is determined (see step 230) that the opticalenergy interacting with the optical filter 120 is within the transmittedspectrum, then it must next be determined what direction the opticalenergy came from (step 240). If the optical energy that is within thetransmitted spectrum entered (or interfaced with) the optical filterback face 122, then the optical energy transmits through the opticalfilter 120 and into the phosphor layer 135 to interact with the phosphorlayer (step 245). However, if the optical energy that is within thetransmitted spectrum entered (or interfaced with) the optical filterfront face 121, then the optical energy transmits through the opticalfilter 120 and into the LED optical source 110 (step 210)

Next, it is determined if the optical energy that enters (or interactswith) the phosphor layer is within the stimulated spectral width (step250). The optical energy that interacts with the phosphor layer 135 thatis not within the stimulated spectral width passes through the phosphorlayer and exits the phosphor layer through the phosphor layer front face136 (step 255)

For the optical energy that enters (or interacts with) the phosphorlayer 135 that is within the stimulated spectral width, it is nextdetermined if the optical energy is absorbed by the phosphor (step 260).If the optical energy that enters (or interacts with) the phosphor layer135 and is within the stimulated spectral width is not absorbed by thephosphor, the optical energy transmits through the phosphor layer 135and exits the phosphor layer through the phosphor layer front face 136(step 265).

If the optical energy that enters (or interacts with) the phosphor layer135 and is within the stimulated spectral width is absorbed by thephosphor, then new optical energy is created (step 270) (i.e., phosphorcreated optical energy). The phosphor created optical energy is at aspectral width that is different than the optical energy that wasabsorbed by the phosphor. In addition. the phosphor created opticalenergy has a 4π steradian angular distribution. Accordingly, thephosphor created optical energy emits out of the phosphor layer frontface 136 and the phosphor layer back face 137. The amount of absorptionis determined by, for example, but not limited to. the amount ofphosphor doping, the thickness of the phosphor layer, the concentrationof the phosphor particles within the suspension medium, etc. In apreferred embodiment of the invention, the amount of absorption isregulated to optimize a desired CCT range. CRI value, and/or opticalenergy produced by the white light system 100.

For the phosphor created optical energy, it is next determined if theoptical energy emits out the phosphor layer front face 136 (step 275).If the phosphor created optical energy emits out the phosphor layerfront face 136, then the optical energy passes through to theconcentrator entrance aperture 142 (Step 280). If the phosphor createdoptical energy emits out the phosphor layer back face 137, then theoptical energy transmits to the optical filter front face 121 (Step 285)and interacts with the optical filter (i.e., reflect or transmit) (step225).

There are three aforementioned paths that optical energy exits phosphorlayer front face 136, namely, from optical energy outside the stimulatedrange (see step 255), from non-absorbing optical energy within thestimulated range (see step 265), and phosphor created optical energy(see step 280) and enters the concentrator entrance aperture 142. In apreferred embodiment of the invention, the combination of the opticalenergy originating from these three paths, when properly mixed withinthe concentrator 140, produce white light. In addition, in analternative embodiment of the invention, the contribution of opticalenergy from each path is modified to optimize a desired CCT range, CRIvalue, and/or optical energy produced by the white light system 100.

The concentrator 140 aligns and outputs the optical energy captured byway of the aforementioned three paths (step 290). In addition, theconcentrator 140 mixes the optical energy captured at the concentratorentrance aperture 142 in so that the optical energy emitted by theconcentrator exit aperture 141 is spatially uniform. The nature of thenon-imaging concentrator is to transfer optical energy from one point toanother and from one angular region to another. The non-imaging aspectsof the concentrator provide mixing of the spatial distribution of theoptical energy at the entrance aperture 142 such that the spatialdistribution at the exit aperture 141 is uniform.

The emitted optical energy from the concentrator exit aperture 142, ifleft unobstructed, forms a diverging conical shaped first illuminationregion (step 292). The optical energy in the first illumination patternthen interacts with a secondary optical element 160, which modifies theoptical energy in the first illumination pattern (step 294) to form asecond illumination pattern (step 296).

EXAMPLE

Referring to FIG. 1, in a preferred embodiment of the invention, the LEDoptical source 110 is a combination of two LED optical sources. Thefirst LED optical source 110 is an array of eight CREE Xbright PowerChip LED C470-XB900, which requires 1,125 milliwatts of electric power(i.e., 350 milliamps at 3.5 volts) to produce 150 milliwatts of opticalpower from each LED for optical energy with a spectral width of 440nanometers to 480 nanometers and a spectral peak at 460 nanometers. Thetotal optical power for the first LED optical source is therefore 1,350milliwatts. The first LED optical source represents the stimulatedoptical energy. The second LED optical source 110 is one LumiledsHWFR-B515, which requires 700 milliwatts of electric power (i.e., 250milliamps at 2.8 volts) to produce 150 milliwatts of optical power fromthe LED for optical energy with a spectral width of 620 nanometers to660 nanometers and a spectral peak at 640 nanometers. The second LEDoptical source represents the non-stimulated optical energy. The totaloptical power for the combination of the First and second LED opticalsources is therefore 1,500 milliwatts. The optical energy emits a two pisteradian angular distribution at the LED optical source front face 111and the LED optical source back face 112. A reflector 130 is placed atthe LED optical source back face 112 to reflect the two pi steradianangular distribution back into the LED and out through the LED opticalsource front face 111, minus any loss due to scattering and absorption,etc., thereby increasing the optical energy. The reflector has areflected spectral width of 380 nanometers to 750 nanometers.

In a preferred embodiment of the invention, the optical filter 120 iscoated on the LED optical source front face and the optical filterreflects optical energy between 500 nanometers to 750 nanometers andtransmits optical energy between 380 nanometers and 500 nanometers. In apreferred embodiment of the invention, the optical filter reflects andtransmits optical energy according to the a particular reflectedspectrum width and a particular transmitted spectral width from both theoptical filter front face 121 and the optical filter back face 122. Inother words the filtering characteristics for the optical filter 120 arethe same, independent on what direction the optical energy enters (orinteracts with) the filter. In the example, since the LED providesoptical energy between 440 nanometers and 480 nanometers, the LEDoptical source 110 created optical energy will pass through the opticalfilter back face 122 and into phosphor layer 135 unencumbered, but fornominal absorption and scattering losses.

In a preferred embodiment of the invention, the phosphor layer 135 is amixture of phosphor and UV curable epoxy. The phosphor is PhosphorTechnologies CS:YAG and the UV curable epoxy is Masterbond UTV 15-7. Thephosphor layer 135 is 0.254 millimeters thick and has a phosphor dopingpopulation of one part phosphor in twenty parts epoxy by weight. In thecontinuing example, the phosphor layer has a stimulated spectral peak of470 nanometers, a non-stimulated spectral peak of 640 nanometers andwhen stimulated, produces optical energy over a 4 pi steradian angulardistribution with a spectral width of 500 nanometers to 750 nanometers,with a spectral peak of 550 nanometers and emits out of the phosphorlayer back face 137 and the phosphor layer front face 136.

The optical energy created by the phosphor layer 135 that is emitted outof the phosphor layer back face 137 (i.e., within spectral width 500nanometers to 750 nanometers) reflects off of the optical filter frontface 121 (i.e., since the optical energy is within the reflectedspectrum of the optical filter) and then interacts with the phosphorlayer 135. Since the reflected optical energy is within the spectralwidth of 500 nanometers to 750 nanometers, the optical energy transmitsthrough the phosphor layer 135 and exits through the phosphor layerfront face 136, but for optical energy lost due to absorption andscattering. In a preferred embodiment of the invention, Side loss,within the phosphor layer 135, is reduced by coating the side walls withreflective material.

In the example, a small proportion of optical energy will exit thephosphor layer back face 137 within the spectral width of 380 nanometersto 500 nanometers due to scattering during the interaction with thephosphor layer 135. However, this energy is ultimately redirected by thewhite light system 100. Specifically, this optical energy (i.e., withinspectral width 380 nanometers to 500 nanometers) transmits through theoptical filter 130 (i.e., enters the optical filter front face 121,transmits through the filter, and exits through the optical filter backface 122), enters the LED optical source 110, and then reflects off ofthe reflector 130 (since the reflector 1 A has a reflected spectrum of380 nanometers to 750 nanometers). The reflected optical energy thentravels back through the LED optical source 110, through the opticalfilter 130, and then interacts with the phosphor layer 135. Thistelescoping circular path for the optical energy contributes to theoptical power (intensity), the CCT range, and the CRI value associatedwith the optical energy emitting out of the phosphor layer front face136 at each revolution.

In addition, a partial amount optical energy within the phosphor layerstimulated spectral width will not be absorbed by the phosphor layer andpass through the phosphor layer and exit at the phosphor layer frontface 136. The five paths of optical energy, the revolving path, thestimulated and absorbed path, the stimulated but not absorbed path, thenon stimulated path, and the optical filter reflected path allcontribute to the optical energy, the CCT range, and the CRI valueassociated with the optical energy emitting out of the phosphor layerfront face 136.

The phosphor layer emits 450 milliwatts of optical energy with a 2πsteradian distribution out the phosphor layer front face 136 with aspectral width of 440 nanometers to 730 nanometers with a primary peakat 460 and 640 nanometers (i.e., primarily from the LED created opticalenergy) and a secondary peak at 550 nanometers (i.e., primarily from thephosphor layer created optical energy), which produces a CCT (7300K) of4200K and a CRI value of 92, which corresponds to white light.

Then, the concentrator entrance aperture 142 captures the 2π steradianoptical energy emitting from the phosphor layer front face 136, mixesand aligns the optical energy, and then emits 432 milliwatts ofspatially uniform white light with a CCT of 4200K and a CRI value of 92,into a diverging first illumination region 150.

The optical energy in the first illumination pattern then interacts witha secondary optical element 160. which modifies the optical energy inthe first illumination region (step 294) to form a second illuminationregion (step 296). In a preferred embodiment of the invention, thesecond illumination region contains a target 180, which is illuminatedwith optical energy present in the second illumination region 170.

FIG. 3 illustrates a LED curing system 300 according to a preferredembodiment of the invention for curing, bonding, and/or sealing lightsensitive targets. The LED curing system 300 includes a LED opticalsource 310, a heat spreader 320, a heat sink 330, a concentrator 340, alight guide 350, power source 360, electronic controls 370, and a cyclecontroller 380, an illumination region 390, and a target 395.

LED optical source 310 is optically coupled to concentrator 340. LEDoptical source 310 includes a LED, which emits optical energy over a 4πsteradian angular distribution, at a particular CCT range, at aparticular wavelength spectrum and at a particular intensity. The CCTrange includes the visible light spectrum, the ultraviolet lightspectrum and the infrared light spectrum.

In an alternative embodiment, the LED optical source 310 includes a backreflector to capture additional optical energy and direct the opticalenergy to the concentrator 340. In an alternative embodiment of theinvention, the LED optical source includes an array of LED's. In apreferred embodiment of the invention, optical requirements of theillumination region 390 determine the type, quantity and location of theLED's within the array that are located within the LED optical source310.

In an alternative embodiment of the invention, the LED optical source310 includes an array of LED's, which are positioned in an optimallocation to increase thermal dissipation. In an alternative embodimentof the invention, the LED optical source 310 includes an array of LED's,which are positioned in an optimal location to obtain a desired CCTrange in the illumination region 390. In an alternative embodiment ofthe invention, LED optical source 310 emits optical energy that matchesthe absorption CCT range of a particular light curing material.

In an alternative embodiment of the invention, the LED optical source310 is optimized to satisfy particular thermal energy requirements ofthe LED curing system 300. Many curing systems are utilized in medicalenvironments, which are sensitive to thermal energy (i.e., increasetemperature).

The heat spreader 320 is thermally attached to the LED optical source310 and pulls the thermal energy away from the thermal energy source (i.e., the LED optical source 310). Increased thermal dissipation providesfor increased electric efficiency within the LED. In a preferredembodiment of the invention, the heat spreader 320 material includesdiamond. Diamond has a high thermal conductivity and thus permit higheroperating currents to be used without increasing the temperature of theLED. In an alternative embodiment of the invention, the heat spreader320 material includes any material with a high conductivity, such as,but not limited to copper, aluminum, etc. The heat spreader 320 isthermally attached to the heat sink 330.

The heat sink 330 is thermally attached to the heat spreader. In analternative embodiment, the heat sink 330 acts a casing for the LEDcuring system 330. In an alternative embodiment. the heat sink 330 actsas a light guide to guide optical energy present in the illuminationregion 390.

In an alternative embodiment, the heat sink 330 provides an integratinganchor for the light guide 350. In an alternative embodiment, the heatsink 330 is cooled by water to effectuate the dissipation of thermalenergy. In an alternative embodiment, the heat sink 330 uses conductivecooling to dissipate thermal energy. In an alternative embodiment of theinvention. the size, shape, and material of the heat sink is optimizedto maximize the amount of thermal energy that the heat sink 330dissipates.

The concentrator 340 is positioned to capture optical energy emittedfrom the LED optical source 310 and includes an entrance aperture and anexit aperture. Optical energy is received from the LED optical source310 via the concentrator entrance aperture. The concentrator then alignsthe received optical energy and then outputs the optical energy throughthe concentrator exit aperture to the light guide 350.

In a preferred embodiment of the invention, the concentrator 340 is anon-imaging concentrator. In a preferred embodiment of the invention,the concentrator 340 is a CPC shaped concentrator. In a preferredembodiment of the invention, the concentrator is flush with the LEDoptical source 310. In a preferred embodiment of the invention, theconcentrator 340 includes a reflective coating on the inside surface toprovide for an optically efficient transfer of optical energy fromconcentrator entrance aperture to the concentrator exit aperture. In apreferred embodiment of the invention, the concentrator 340 includes adielectric material to provide for an optically efficient transfer ofoptical energy from concentrator entrance aperture to the concentratorexit aperture. In a preferred embodiment of the invention, any areabetween the LED light source 310 and the concentrator 340 is filled withan optically clear cement or gel to match the refractive index (e.g.,when the concentrator is filled with a dielectric material.).

In a preferred embodiment of the invention, the concentrator is made ofa dielectric material. In a preferred embodiment of the invention, theconcentrator is made of a dielectric material that has a sufficientindex of refraction to permit total internal reflection. In a preferredembodiment of the invention, the concentrator is made of a hollowreflector. In a preferred embodiment of the invention, the concentratoris made of a dielectric material.

The light guide 350 is positioned to receive aligned optical energy fromthe exit aperture of the concentrator 340. The light guide has anentrance aperture, which receives optical energy from the concentrator340, and an exit aperture, which emits optical energy into anillumination region 390. In a preferred embodiment of the invention, thelight guide 350 delivers the optical energy to an illumination region.

The power source 360 is electrically attached to the LED optical source310 and provides electricity to the LED optical source 310. In apreferred embodiment of the invention, the power source 360 is abattery. In a preferred embodiment of the invention, the power source360 is a hand held battery. In a preferred embodiment of the invention,the power source 360 is a battery that transfers 3,500 milliwatts ofelectrical power to the LED optical source. In a preferred embodiment ofthe invention, the power source 360 is positioned in the base of the LEDcuring system 300. To satisfy the curing application requirements, suchas, but not limited to, CCT range intensity requirements, continuoususe, etc., conventional systems use brute force (i.e., large opticalsources, that emit large amounts of heat and require large amounts ofpower) since the conventional systems have poor electrical and opticalefficiency. Thus, conventional systems cannot satisfy applicationrequirements using a hand-sized off the shelf battery. In a preferredembodiment of the invention, the power source 360 is a rechargeablebattery. In a preferred embodiment of the invention, the power source360 is a wall plug.

The electronic controls 370 provide a user with control over theduration, the intensity and the CCT range of the optical energy emittedfrom the LED curing system 300 onto the target 395. In a preferredembodiment of the invention, the electronic controls can cycle on andoff particular LED's within the LED optical source. In a preferredembodiment of the invention, the electronic controls can increase ordecrease the electrical current to the LED optical source 310. In apreferred embodiment of the invention, the electronic controls canincrease or decrease the electrical current to a particular LED withinthe LED optical source 310.

In a preferred embodiment of the invention, the electronic controlsprovide pulsing of the LED optical source 310 for a prescribed dutycycle. In a preferred embodiment of the invention, the electroniccontrols provide pulsing of the LED optical source 310 for a prescribedpulse duration. In a preferred embodiment of the invention, theelectronic controls provide pulse width modulation (“PWM”) of the LEDoptical source 310. PWM provides a constant drain on the power source asa function of the power source lifetime, which results in a constantoutput electrical power to the LED optical source 310 over the entirepower source life cycle.

The cycle controller 380 is electrically attached to the power supply.Engaging the cycle controller 380 allows a user to initiate the LEDcuring system for one cycle. In a preferred embodiment of the invention,a cycle is ten seconds on and ten seconds off.

The illumination region is optically coupled to the light pipe 350. Theillumination region begins at the exit aperture of the light pipe andcontinues in a diverging region. In a preferred embodiment of theinvention, the optical power emitting at the exit aperture of the lightpipe 350 is approximately ten to eighteen percent of the inputelectrical power.

The target 395 is positioned within the illumination region 390. In apreferred embodiment of the invention, the target 395 is positionedwithin the near field of the illumination region 390. In a preferredembodiment of the invention, the target includes a light sensitivematerial that cures when exposed to the optical energy within theillumination region 390.

In a preferred embodiment of the invention, the target includes asealant that cures when introduced to the optical energy within theillumination region 390. In a preferred embodiment of the invention, thetarget includes an adhesive that cures when introduced to the opticalenergy within the illumination region 390. In a preferred embodiment ofthe invention, the target includes a composite that cures whenintroduced to the optical energy within the illumination region 390. Ina preferred embodiment of the invention, the target includes lightcuring sealants used in lung surgery that cures when introduced to theoptical energy within the illumination region 390.

In a preferred embodiment of the invention, the target includes lightcuring sealants used in dentistry when introduced to the optical energywithin the illumination region 390. In a preferred embodiment of theinvention, the target includes a composite used in dentistry that cureswhen introduced to the optical energy within the illumination region390.

In a preferred embodiment of the invention, the target includes a lightsensitive material for bonding that bonds when introduced to the opticalenergy within the illumination region 390. In a preferred embodiment ofthe invention, the target includes a light sensitive material forsealing that seals when introduced to the optical energy within theillumination region 390. In a preferred embodiment of the invention, thetarget includes a light sensitive material for bonding that bonds dentalfixtures and/or dental implants when introduced to the optical energywithin the illumination region 390. In a preferred embodiment of theinvention, the target includes a light sensitive material for sealingthat seals dental fixtures and/or dental implants when introduced to theoptical energy within the illumination region 390. Light sensitivematerials are used for bonding and/or sealing. For instance, the dentalmarket has chosen light sensitive adhesives for bonding and sealing ofdental fixtures and other dental implants.

In a preferred embodiment of the invention, the target includesadhesives that cure when introduced to ultra-violet optical energywithin the illumination region 390. In a preferred embodiment of theinvention, the target includes adhesive used in industrial applicationsthat cures when introduced to ultra-violet optical energy within theillumination region 390 In a preferred embodiment of the invention, thetarget includes a biocompatible material that cures when introduced tothe optical energy within the illumination region 390. In a prefer-redembodiment of the invention, the target includes a biocompatiblematerial located topically that cures when introduced to the opticalenergy within the illumination region 390. In a preferred embodiment ofthe invention, the target includes a biocompatible material locatedwithin a body cavity that cures when introduced to the optical energywithin the illumination region 390.

In an alternative embodiment of the LED curing system 300, the LEDcuring system 300 is portable. In an alternative embodiment of the LEDcuring system 300. the LED curing system 300 weighs 90 grams. In analternative embodiment of the LED curing system 300. the LED curingsystem 300 has dimensions of 146 millimeters long by 18 millimetersdiameter. In an alternative embodiment of the LED curing system 300, theLED curing system 300 is disposable.

FIG. 4 illustrates a LED photodynamic therapy system 400 according to apreferred embodiment of the invention. The LED photodynamic therapy(“PDT”) curing system 400 includes a LED optical source 410, a heatspreader 420, a heat sink 430, a concentrator 440, power Source (notshown), an illumination region 460, a therapeutic region 470 and atarget (not shown ).

LED optical source 410 is optically coupled to concentrator 440. LEDoptical source 410 includes a LED, which emits optical energy over a 4πsteradian angular distribution at a particular CCT range, a particularwavelength spectrum, and at a particular intensity. The CCT rangeincludes the visible light spectrum, the ultraviolet light spectrum andthe infrared light spectrum.

In an alternative embodiment, the LED optical source 410 includes a backreflector to capture additional optical energy and direct the opticalenergy to the concentrator 440. In an alternative embodiment of theinvention, the LED optical source 410 includes an array of LEDs. In analternative embodiment of the invention, optical requirements of theillumination region 460 determine the type, quantity and location of theLED that is located within the LED optical source 410.

In an alternative embodiment of the invention, the LED optical source410 includes an array of LEDs, which are positioned in an optimallocation to increase thermal dissipation. In an alternative embodimentof the invention, the LED optical source 410 includes an array of LEDs,which are positioned in an optimal location to obtain a desiredwavelength spectrum in the illumination region 460. In an alternativeembodiment of the invention, the LED optical source 410 includes anarray of LEDs, which are positioned in an optimal location to obtain adesired wavelength spectrum in the illumination region 390.

In a preferred embodiment of the invention, the wavelength spectrum ofthe optical energy in the illumination region 460 is absorbed by aphotosensitizer or drug compound. PDT involves injecting or dopingbiomaterial, such as, but not limited to, blood, cells, tissue, etc.with a photosensitizer or drug compound. Photosentizers and drugcompounds, atoms, molecules, etc., responds to particular wavelengths ofoptical energy. When the photosensitizer or drug compound is exposed toa particular wavelength of optical energy, it absorbs the optical energyand emits a singlet oxygen or undergoes some other photochemicalreaction. The singlet oxygen oxidizes critical elements of neoplasticcells (i.e., of the tumor cells). Thus, the wavelength spectrum of theoptical energy within the illumination region 460 is determined by whatwavelength will alter the photosensitizer (and, ultimately, the cell) ordrug compound.

In a preferred embodiment of the invention, the wavelength spectrum ofthe optical energy in the illumination region 460 penetrates tissuelocated in the target 480. Optical energy with longer wavelengthspenetrate tissue deeper than optical energy with shorter wavelengths.Thus, for example, the photosensitizer porfimer sodium has a peakabsorption in the area of 405 nanometers (blue-violet) and another peakabsorption in the area of 630 nanometers (red). Since red has a longerwavelength than blue-violet, the red optical energy will penetrate thetissue deeper than the blue-violet optical energy. Thus, the LED PDTsystem uses a LED optical system that produces optical energy with apeak at 630 nanometers.

In an alternative embodiment of the invention, LED optical source 410emits optical energy that matches the absorption peak of a particularPDT photosensitizer. In an alternative embodiment of the invention, theoptical energy produced by the LED PDT system corresponds to theabsorption peak with the longest wavelength.

In an alternative embodiment of the invention, the LED optical source410 is optimized to satisfy particular thermal energy requirements ofthe LED curing system 300. Many curing systems are utilized in medicalenvironments, which are sensitive to thermal energy (i.e., increasetemperature).

In an alternative embodiment of the invention, the LED is bonded to theheat spreader 420 with a thermally conductive material. In analternative embodiment of the invention. the LED is soldered to the headspreader 420. In an alternative embodiment of the invention. the LED isbonded to the heat sink 430 with a thermally conductive material. In analternative embodiment of the invention, the LED is soldered to the headsink 430.

The heat spreader 420 is thermally attached to the LED optical source410 and pulls the thermal energy away from the thermal energy source(i.e., the LED optical source 410). Increased, thermal dissipationprovides for increased electrical efficiency within the LED. In apreferred embodiment of the invention, the heat spreader 410 materialincludes diamond. Diamond has a high thermal conductivity and thuspermits higher operating electrical currents to be used withoutincreasing the temperature of the LED. In an alternative embodiment ofthe invention, the heat spreader 420 material includes any material witha high conductivity, such as, but not limited to copper, aluminum, etc.The heat spreader 420 is thermally attached to the heat sink 430.

The heat sink 430 is thermally attached to the heat spreader 420. In analternative embodiment of the invention, the heat sink 430 acts as acasing for the LED PDT system 400. In an alternative embodiment, theheat sink 430 acts as a light guide to guide optical energy present inthe illumination region 460.

In an alternative embodiment of the invention, the heat sink 430 iscooled by water to effectuate the dissipation of thermal energy. In analternative embodiment, the heat sink 430 uses conductive cooling todissipate thermal energy. In an alternative embodiment of the invention,the size, shape, and material of the heat sink is optimized to maximizethe amount of thermal energy that the heat sink 430 dissipates.

The concentrator 440 is positioned to capture optical energy emittedfrom the LED optical source 410 and includes an entrance aperture and anexit aperture. Optical energy is received from the LED optical source410 via the entrance aperture of the concentrator 440. The concentrator440 then aligns the received optical energy and then outputs the opticalenergy through the exit aperture of the concentrator 440 to theillumination region 460.

In a preferred embodiment of the invention, the concentrator 440 is anon-imaging concentrator. In a preferred embodiment of the invention,the concentrator 440 is a compound parabolic concentrator (“CPC”) shapedconcentrator. In a preferred embodiment of the invention, theconcentrator is flush with the LED optical source 410. In a preferredembodiment of the invention. the concentrator 440 includes a reflectivecoating on the inside surface to provide for an optically efficienttransfer of optical energy from entrance aperture of the concentrator tothe exit aperture of the concentrator. In a preferred embodiment of theinvention, the concentrator transfers optical energy from the entranceaperture of the concentrator 440 to the exit aperture of theconcentrator 440. In a preferred embodiment of the invention, any areabetween the LED optical source 410 and the concentrator 440 is filledwith an optically clear cement or gel to match the refractive index(e.g., when the concentrator is filled with a dielectric material.).

In a preferred embodiment of the invention, the concentrator is made ofa dielectric material. In a preferred embodiment of the invention, theconcentrator is made of a dielectric material that has a sufficientindex of refraction to permit total internal reflection. In a preferredembodiment of the invention, the concentrator is made of a hollowreflector. In a preferred embodiment of the invention, the concentratoris made of a dielectric material.

The power source (not shown) is electrically attached to the LED opticalsource 410 and provides electricity to the LED optical source 410. In apreferred embodiment of the invention. the power source is a battery. Ina preferred embodiment of the invention, the power source is a hand heldbattery. In a preferred embodiment of the invention, the power source isa battery that transfers 600 watts of electrical power to the LEDoptical source. In a preferred embodiment of the invention, the powersource is a rechargeable battery. In a preferred embodiment of theinvention, the power source is a wall plug.

The illumination region is optically coupled to the exit aperture of theconcentrator 440. The illumination region begins at the exit aperture ofthe concentrator and continues in a diverging region. In a preferredembodiment of the invention, the optical power emitting at the exitaperture of the light pipe 350 is approximately ten to eighteen percentof the input electrical power.

The therapeutic area is provided by an LED PDT system with multiple LEDoptical sources each with a dedicated concentrator, and each providing aunique illumination region. Each individual subsystem is referred to asa PDT light engine. In an alternative embodiment of the invention, themultiple illumination regions partially overlap.

The target (not shown) is positioned within the illumination region 460.The target is positioned within the therapeutic area 470. In a preferredembodiment of the invention, the target is positioned within the nearfield of the illumination region 460. In a preferred embodiment of theinvention, the target is positioned within the far field of theillumination region 460.

In a preferred embodiment of the invention, the target includes aphotosensitizer that undergoes a photochemical reaction when introducedto the optical energy in the therapeutic area 470. In a preferredembodiment of the invention, the target includes a drug compound thatundergoes a photochemical reaction when introduced to the optical energyin the therapeutic area 470.

FIG. 5 illustrates a multi-wavelength LED array illumination system 500according to an alternative embodiment of the invention. Themulti-wavelength LED array illumination system 500 includes a LED array510, a heat sink 520, a ceramic board 530, an array of concentrators540, a light integrator 550 and an illumination region 560 and a target570.

The LED array 510 comprises LED groups 512. Each LED group comprises asingle LED or an array of smaller LED's and emits optical energy over a4π steradian angular distribution, at a particular CCT range, at aparticular wavelength spectrum and at a particular intensity. The CCTrange includes the visible light spectrum, the ultraviolet lightspectrum and the infrared light spectrum. Each LED group 512 isoptically coupled to a unique concentrator.

In an alternative embodiment of the invention, the wavelength spectrumemitted by each LED group 512 is the same. In an alternative embodimentof the invention, the LED groups 512 do not all emit the same wavelengthspectrum. In an alternative embodiment of the invention, the wavelengthspectrums emitted by each LED group 512 are optimized to provide adesired mix of wavelengths, such as, but not limited to, white light, oryellow light, etc. In an alternative embodiment of the invention, theLEDs are approximately 1.0 to 1.2 millimeters squared.

In an alternative embodiment of the invention, near field and far fieldcolor mixing is provided by distributing those LED groups 512, whichemit like wavelength spectrums, throughout the LED array 510. In analternative embodiment of the invention, the intensity of each LED groupcan be individually monitored. In an alternative embodiment of theinvention, the intensity of each LED group 512 can be individuallyincreased, decreased, turned off or turned on. In an alternativeembodiment of the invention, the intensity of each LED within each LEDgroup 512 can be individually increased, decreased, turned off or turnedon.

In an alternative embodiment of the invention, the LED's within each LEDgroup 512 includes a back reflector to capture additional optical energyand direct the optical energy to a corresponding concentrator. In analternative embodiment of the invention, optical requirements of theillumination region 560 determine the type, quantity and location of theLED's within LED array.

In an alternative embodiment of the invention, the LED groups 512 arepositioned in an optimal location to increase thermal dissipation. In analternative embodiment of the invention. the LED groups 512 arepositioned in an optimal location to obtain a desired CCT range in theillumination region 560.

The heat sink 520 is thermally attached to each LED group 512. In analternative embodiment of the invention, the LED within each LED group512 are thermally attached to the heat sink 520 by a thermallyconductive material, such as, but not limited to solder, conductiveepoxy, etc.

In an alternative embodiment of the invention, the heat sink 520 iscooled by water to effectuate the dissipation of thermal energy. In analternative embodiment of the invention. the heat sink 520 usesconductive cooling to dissipate thermal energy. In an alternativeembodiment of the invention, the size, shape, and material of the heatsink is optimized to maximize the amount of thermal energy that the heatsink 520 dissipates.

In an alternative embodiment, the heat sink 520 anchors themulti-wavelength LED array illumination system 500 to a host, such as,but not limited to a mechanical device, a human, a casing, etc.

In an alternative embodiment of the invention, the heat sink includesfins. Fins provide greater surface area for increased thermal energydissipation. In an alternative embodiment of the invention, forcedconvection is used to dissipate thermal energy from the multi-wavelengthLED array illumination system 500 and, more specifically, thermal energyfrom the heat sink 520 and/or thermal energy from each LED group 512.

In an alternative embodiment of the invention, the heat sink 520material includes copper. In an alternative embodiment of the invention,the heat sink 520 material includes aluminum. In an alternativeembodiment of the invention, the heat sink 520 material includesmaterial that has a high thermal and electrical conductivity.

In an alternative embodiment of the invention, a heat spreader ispositioned between the heat sink 520 and the LED groups 512. A heatspreader pulls the thermal energy laterally away from the thermal energysource (i. e., the LED groups 512) and, thus, decreases the effectiveheat flux (heat power/unit area) impingent upon the heat sink 520.Increased thermal dissipation provides for increased electric efficiencywithin the LED groups 512. In a preferred embodiment of the invention,the heat spreader material includes diamond. Diamond has a high thermalconductivity (relative to the heat sink 512). In an alternativeembodiment of the invention, the heat spreader material includes anymaterial with a high conductivity, such as, but not limited to copper,aluminum, etc. In a preferred embodiment of the invention, the heatspreader is thermally attached to the heat sink 520.

The ceramic board 530 provides an electrical path to the LED's withinthe LED groups 512. The ceramic board is mounted on the heat sink 520and provides cut-outs through which the LED's within the LED groups 512are mounted to the heat sink 520. The ceramic board includes metalizedtraces. In an alternative embodiment of the invention, a heat spreadercontains a cutout or window which provide the LED groups electricalcontact to the ceramic board 530 and the heat sink 520.

In an alternative embodiment of the invention, the N-type electricalcontact is directly bonded to the heat sink 520. In an alternativeembodiment of the invention, the N-type electrical contact is wirebonded to the heat sink 520 from the top of the LED die within the LEDgroup 512. In an alternative embodiment of the invention, the P-typecontacts are wire bonded to electrical traces located on the ceramicboard 530. An electrical power source is electrically connected to theheat sink 520.

The array of concentrators 540 includes an individual concentrator 542for each LED group 512 Each concentrator 542 is optically coupled to thecorresponding LED group 512. Each concentrator 542 is positioned tocapture optical energy emitted from each LED group 512 and includes anentrance aperture and an exit aperture. Optical energy is received fromeach LED group 512 via the entrance aperture of each concentrator 542.Each concentrator 542 then aligns the received or captured opticalenergy from the corresponding LED group 512 and then outputs the alignedoptical energy through the exit aperture of each concentrator 542.

In a preferred embodiment of the invention, each concentrator 542 is anon-imaging concentrator. In a preferred embodiment of the invention,each concentrator 542 is a CPC concentrator. In a preferred embodimentof the invention, each concentrator 542 is flush with the correspondingLED groups 512.

In an alternative embodiment of the invention, a non-imagingconcentrator 542 is constructed with a high order polynomial surfacerepresenting the attributes of the non-imaging concentrator form. In analternative embodiment of the invention, the aspheric sag equation istuned to match an appropriate non-imaging concentrator form. In analternative embodiment of the invention, any mathematicalrepresentations that approximate the ideal non-imaging concentratorprovides the concentrator profile.

In a preferred embodiment of the invention, each concentrator 542includes a reflective coating on the inside surface to provide for anoptically efficient transfer of optical energy from the entranceaperture of each concentrator 542 to the exit aperture of eachconcentrator 542. In a preferred embodiment of the invention, theconcentrator 542 includes a dielectric material to provide for anoptically efficient transfer of optical energy from the entranceaperture of each concentrator 542 to the exit aperture of eachconcentrator 542. In a preferred embodiment of the invention, any areabetween the each LED group 512 and each corresponding concentrator 542is filled with an optically clear cement or gel to match the refractiveindex (e.g., when the concentrator is filled with a dielectricmaterial.).

In a preferred embodiment of the invention, each concentrator 542includes a dielectric material. In a preferred embodiment of theinvention, each concentrator 542 includes a dielectric material that hasa sufficient index of refraction to permit total internal reflection. Ina preferred embodiment of the invention, each concentrator 542 is madeof a hollow reflector. In a preferred embodiment of the invention, eachconcentrator 542 is made of a dielectric material.

In an alternative embodiment of the invention, the array ofconcentrators 540 includes nineteen concentrators. In a preferredembodiment of the invention, the nineteen concentrators 542 arepositioned in hexagonal close pack array. The position of theconcentrators dictates the positions of the LED groups.

A single LED and single concentrator system that emits the same tosimilar optical power as the LED and concentrator array system uses thesame amount of electrical power. However, by using an array of LED's andconcentrators, the thermal energy created by the LED's is more easilydissipated due to the geometrical distribution of the LEDs' positions.In other words, the single system has large focused amount of thermalenergy at one point (i.e., the thermal flux is isolated in one spot),whereas the array system has smaller amounts of optical energy disbursedover numerous locations (i.e., the heat flux is spread out).Furthermore, since array system more efficiently dissipates heat, theoptical power is not reduced due to electrical inefficiency whencompared the optical power created by the single system.

In an alternative embodiment of the invention, the LED and concentratorarray system when compared to a system with one LED and one concentratorand provide same to similar amounts of optical power and angulardistribution, the LED and concentrator array system is significantlyshorter than the single LED and once concentrator system.

In an alternative embodiment of the invention, a phosphor layer isplaced between a concentrator 542 and light group 512. The phosphorlayer creates optical energy at a specific wavelength range whenstimulated by optical energy of a different wavelength range. In analternative embodiment of the invention, the use of a phosphor layer isused to optimize the output wavelength of the multi-wavelength LED arrayillumination system 500.

The light pipe 550 is optically coupled to the exit apertures of thearray concentrators 542. The multi-sided light pipe that interfaces tothe array of concentrators, assures that the near field intensity at itsoutput will be uniformly distributed over its exit face. In analternative embodiment of the invention, the far field intensity isuniform when the entrance apertures of the array of concentrators 542are uniformly filled.

In an alternative embodiment of the invention, the optical efficiency ofthe multiwavelength LED array illumination system 500 is optimized bypositioning the LED and concentrator array in the same shape as theentrance aperture of the light pipe.

In an alternative embodiment of the invention, the light pipe 550 mixesthe optical energy from the exit apertures of each concentrator 542. Inan alternative embodiment of the invention, the light pipe is faceted,which optimizes the mixing efficiency. A circular light pipe is a poormixer of optical energy. A faceted light pipe is a more efficient mixerthan a circular light pipe. However, the higher the number of facets,the closer the circumference approaches a circle, the mixing efficiencywanes. In addition, a light pipe with an even number of facets is a moreefficient mixer than a light pipe with an odd number of facets. Theoptimum number of facets (i.e., for optimum mixing) is eight. In analternative embodiment of the invention, the light pipe 550 has eightfacets or sides. In order to fully benefit from the optimal mixingefficiencies. however, the entrance aperture of each concentrator in thearray must be fully filled and the array shape must correspond to thehexagonal shape of the light pipe. In an alternative embodiment of theinvention, the LED and concentrator array is hexagonal in shape. In analternative embodiment of the invention, the entrance aperture of eachconcentrator 543 is fully filled. In an alternative embodiment of theinvention, the light pipe 550 is hexagonal.

In an alternative embodiment of the invention, the array ofconcentrators 540 is molded as one unit. Molding the concentratorstogether reduce optical losses. In an alternative embodiment of theinvention, the array of concentrators 540 and the light pipe are allmolded together as one unit.

In an alternative embodiment of the invention, any optical element thatdirects or modifies optical energy is optically coupled to the exitapertures of the concentrators 542 in the array of concentrators 540.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 includes a single concentrator. In analternative embodiment of the invention, the multi-wavelength LED arrayillumination system 500 includes a prism to capture and direct theoptical energy exiting the exit aperture of a single concentrator. In analternative embodiment of the invention, the prism directs opticalenergy orthogonally.

The illumination region 560 is optically coupled to exit face of thelight pipe 550. The illumination region begins at the exit face of thelight pipe. In a preferred embodiment of the invention, the opticalpower emitting at the exit aperture of the light pipe 350 isapproximately ten to eighteen percent of the input electrical power. Inan alternative embodiment of the invention, the illumination region 560is optically coupled to the exit apertures of each concentrator 542. Inan alternative embodiment of the invention, the illumination region 560is optically coupled to a single exit aperture.

The target 570 is positioned within the illumination region 560. In apreferred embodiment of the invention, the target 570 is positionedwithin the near field of the illumination region 560.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 produces white light. In an alternativeembodiment of the invention, LED array 510 includes a blue LED, a redLED, and a green LED to produce white light in the illumination region560. In an alternative embodiment of the invention, blue LED is cycledoff and the remaining red LED and green LED combine to produce yellowlight. In an alternative embodiment of the invention, yellow light(i.e., fog lights) is instantly produced from white light by turning offthe blue LED.

The longer wavelength yellow color does not scatter as much as theshorter wavelength blue color. The scattering of the light through thewater particles reduces visibility when driving in foggy or rainyconditions.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 produces optical energy with a CCT rangeof 4100K to 4900K and a CRI value of 92, both of which satisfy the majorsurgical lighting industry requirements.

In an alternative embodiment of the invention, the multi-wave length LEDarray illumination system 500 provides illumination for automotivelighting which includes, but is not limited to, automotive head lights,automotive secondary head lights, automotive fog lights, automotiveindicator lights. In an alternative embodiment of the invention, themulti-wavelength LED array illumination system 500 provides opticalenergy source for automotive illumination lighting and automotiveindicator lighting, etc.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 provides illumination for medical lightingwhich includes, but is not limited to, overhead (or major) surgicallighting, endoscope illumination at the distal end, surgical headlights. PDT illumination, and an UV Bilirubin blanket.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 provides optical energy for dental fieldapplications which include, but are not limited to, curing, toothwhitening, illumination for a portable head light, illumination forintra-oral cameras, etc.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 provides optical energy for consumerapplications which include, but are not limited to, head lighting, bikelighting, high end flashlights, an automotive trouble light, a lighttherapy box, and a miner's head light, etc.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 provides optical energy for safetyapplications, which include, but are not limited to, strobe lighting,beacons, etc.

In an alternative embodiment of the invention, the multi-wavelength LEDarray illumination system 500 provides optical energy for industrialapplications which include, but are not limited to, machine visionlighting, display lighting, UV spot curing light, decorative lightingsystem, food inspection equipment.

While the invention has been described in terms of preferredembodiments, those skilled in the art will recognize that the inventioncan be practiced with modifications within the spirit and scope of theappended claims.

1. An illumination apparatus, said apparatus comprising at least one LEDoptical source having a predetermined spectral output that is emittedover a predetermined solid angle of 2π steradians; at least one phosphorlayer having an entrance surface being configured and arranged tointercept the output from said at least one LED, partially absorb lightwithin said predetermined spectral output of at least one of said LED,and convert it to light having another predetermined spectral output toprovide said beam from said apparatus with a preferred spectral content;and at least one non-imaging concentrator for collecting substantiallyall of the light emitted by said at least one phosphor layer andre-emitting it as a spatially uniform beam having a diverging solidangle smaller than said predetermined solid angle of 2π sterdians, saidnon-imaging concentrator having an entrance aperture, an exit aperture,and a shape that continuously enlarges from said entrance to said exitaperture, said at least one phosphor layer being positioned at and fullyacross said entrance aperture so that said entrance aperture issubstantially uniformly filled by said output of said at least one LEDoptical source, said output of said at least one LED optical sourcebeing directed by said non-imaging concentrator shape to emerge fromsaid exit aperture as said spatially uniform beam of predeterminedspectral output.
 2. White light illumination apparatus, said apparatuscomprising: at least one LED having an output in the blue region of thespectrum; at least one other LED having an output in the red region ofthe spectrum; a phosphor layer having entrance and exit surfaces, saidphosphor layer being configured and arranged to intercept the outputsfrom said LEDs via its entrance surface, partially absorb blue light andconvert it to yellow light, and transmit the unabsorbed blue light,along with the yellow and red light, to form a combined output of whitelight at its exit surface, said white light emerging from said phosphorlayer exit surface over a predetermined solid angle; and a non-imagingconcentrator for collecting substantially all of the white light emittedby said phosphor layer and re-emitting it as a beam having a divergingsolid angle smaller than said predetermined solid angle of said exitsurface, said non-imaging concentrator having an entrance aperture forreceiving the white light emerging from the exit surface of saidphosphor layer and an exit aperture from which said white light emergesspatially and spectrally uniform in the near field of said exitaperture.
 3. The white light illumination apparatus of claim 2 whereinsaid at least one LED having an output in the blue region of thespectrum emits radiation over the range including 440 to 480 nanometerswith a peak at 460 nanometers.
 4. The white light illumination apparatusof claim 3 wherein said at least one LED having an output in the blueregion comprises and array of LEDs.
 5. The white light illuminationapparatus of claim 4 where said array has a total optical power outputof at least 1350 milliwatts.
 6. The white light illumination apparatusof claim 2 wherein said yellow light emitted by said phosphor layerfalls within the range including 500 to 750 nanometers.
 7. The whitelight illumination apparatus of claim 6 wherein said yellow light peaksat approximately 550 nanometers.
 8. The white light illuminationapparatus of claim 2 wherein said other LED having an output in the redregion of the spectrum emits radiation over the range including 620 to660 nanometers.
 9. The white light illumination apparatus of claim 8wherein said other LED having an output in the red region of thespectrum emits peak radiation at approximately 640 nanometers.
 10. Thewhite light illumination apparatus of claim 9 wherein said other LEDhaving an output in the red region of the spectrum emits at least 150milliwatts of optical power.
 11. The white light illumination apparatusof claim 2 wherein said phosphor layer is composed of Yttrium AluminumOxide and Cerium.
 12. The white light illumination apparatus of claim 2wherein said white light has a correlated color temperature (CCT) withinthe range including 4100 to 4900° K.
 13. The white light illuminationapparatus of claim 12 wherein said white light has a color renderingindex (CRI) of at least
 92. 14. The white light illumination apparatusof claim 2 wherein the interfaces between said LEDs, said phosphorlayer, and said non-imaging concentrator are all flat, flush mounted,geometrically matched and index matched to enhance optical efficiency.15. The white light illumination apparatus of claim 2 wherein saidnon-imaging concentrator has a cross-sectional shape in the form of acompound parabola (CPC).
 16. The white light illumination apparatus ofclaim 15 wherein the circumference of said non-imaging concentrator ismultifaceted.
 17. The white light illumination apparatus of claim 2wherein said non-imaging concentrator has a cross-sectional shape in theform of a higher order polynomial.
 18. The white light illuminationapparatus of claim 2 wherein said LEDs have front and back surfaces eachof which emits radiation over a solid angle of 2π steridians.
 19. Thewhite light illumination apparatus of claim 18 further including areflector positioned upstream of said back surfaces of LEDs to interceptradiation emitted by said back surfaces of said LEDs and redirect itdownstream where in can be used at least in part to contribute to saidwhite light output.
 20. The white light illumination apparatus of claim19 wherein said reflector is further configured to transmit infraredradiation traveling upstream so that the heat contained in said infraredradiation is directed outside of said apparatus thereby enhancing itsquantum efficiency.
 21. The white light illumination apparatus of claim19 wherein said reflector comprises a mirror.
 22. The white lightillumination apparatus of claim 20 wherein said reflector comprises amulti-layer optical coating.
 23. The white light illumination apparatusof claim 2 further including an optical band pass filter positionedintermediate said LEDs and said phosphor layer for selectivelycontrolling the spectral content of radiation traveling downstream tosaid phosphor layer and back upstream to said LEDs.
 24. The white lightillumination apparatus of claim 23 wherein said optical band pass filtertransmits blue and red radiation downstream thereof and reflects yellowradiations downstream that would otherwise travel upstream to said LEDs.25. The white light illumination apparatus of claim 2 further includinga heat sink for dissipating heat generated in the process of convertingelectrical energy to optical power to enhance the quantum efficiency ofsaid apparatus.
 26. The white light illumination apparatus of claim 25further including a heat-conducting header for attaching said heat sinkupstream and proximate to said LEDs.
 27. The white light illuminationapparatus of claim 26 wherein said heat conducting header is alsoelectrically conducting.
 28. The white light illumination apparatus ofclaim 27 wherein said heat conducting header is made from the groupconsisting of copper and aluminum.
 29. The white light illuminationapparatus of claim 26 wherein heat-conducting header also includes finsfor enhancing the efficiency with which it dissipates heat.
 30. Thewhite light illumination apparatus of claim 26 further including a heatspreader for distributing heat to said heat-conducting header.
 31. Thewhite light illumination apparatus of claim 30 wherein said heatspreader comprises a thin layer of diamond.
 32. The white lightillumination apparatus of claim 2 further including a secondary opticalcomponent for intercepting the radiation emerging from said non-imagingconcentrator and altering it.
 33. The white light illumination apparatusof claim 32 wherein said secondary optical component is selected for thegroup including prisms, lenses, filters, concentrators, mirrors,refractive elements, diffractive elements, wavelength modifiers,intensity modifiers, phosphor layers, and light pipes.
 34. The whitelight illumination apparatus of claim 32 wherein said secondary opticalcomponent comprises a prismatic element for changing the direction oftravel of said beam emerging from said non-imaging concentrator.
 35. Thewhite light illumination apparatus of claim 2 wherein said beam isadapted for use in applications selected from the group comprisingautomotive lighting including automotive head lights, automotivesecondary head lights, automotive fog lights, automotive indicatorlights medical lighting including. overhead surgical lighting, endoscopeillumination at the distal end, surgical headlights, PDT illumination,and an UV Bilirubin blanket, dental field applications including curing,tooth whitening, illumination for a portable head light, illuminationfor intra-oral cameras, consumer applications including head lighting,bike lighting, high end flashlights, automotive trouble lights, lighttherapy box, and miner's head lights.